Zwinz



Sept. 1, 1959 2,902,229

' PAIRED GRINDING DISCS PARTICULARLY FOR LONG. FIBROUS MATERIALS F. ZWINZ 2 Sheets-Shet l Filed Jan. 16, 1956 JNVENTOR. Franz Z whiz 3? @LM, @296 A9,,

Hfforne F. ZWlNZ Sept. 1, 1959 PAIRED GRINDING DISCS PARTICULARLY FOR LONG FIBROUS MATERIALS Filed Jan. 16, 1956 2 Sheets-Sheet 2 PAIRED GRINDING DISCS PARTICULARLY FOR LONG FIBROUS MATERIALS Franz Zwinz, Neunkirchen, Austria Application January 16, 1956, Serial No. 559,317

Claims priority, application Austria January 20, 1955 3 Claims. (Cl. 241260) This invention relates to grinding discs for mills for material of all kinds, particularly for farms where fibrous material is also to be ground. The grinding means of such mills comprises a pair of hollow-conical discs rotating relatively to each other and the one disc adjacent to the feed pipe is suitably stationary and has a central inlet opening for the material to be ground.

For such mills, grinding discs of that type have been disclosed in which the working formations cooperating with those of the associated disc are arranged in three successive zones from the inner periphery of the disc to the outer rim thereof. In a manner known per se these working formations may comprise, e.g., chopping teeth as comminuting members, then tearing teeth, which are disposed in the central portion of the disc and consist of rib members which control the feed of the material to be ground and have also a comminuting action, and finally discharge grooves formed as fine grinding means in the outer rim portion of the disc. A feature common to all known grinding discs resides in that the working formations are regularly spaced and of uniform shape. In the known grinding discs the material is comminuted by the working formations and is cut and crushed by the tearing teeth, whereafter it passes through the grinding zone and is delivered in ground form at the outer periphery of the disc. These grinding discs have proved satisfactory for fruit, bulbs, maize, cereals etc., but not for fibrous material such as straw, hay, green food and the like, particularly when it is wet; such material will not be comminuted at all in the mill or will leave it in an unevenly comminuted condition and with many longfibrous parts.

The surprising discovery has now been made that discs of that kind can process practically all kinds of material to be ground, including fibrous material, to the highest degree of fineness, if the working members are formed according to the invention in groups in uneven depth, uneven width, irregularly spaced and with irregular configuration.

Extensive tests have shown that the irregular shape of the working members of the grinding disc is the prime cause of the observed advantages of a mill equipped with discs according to the invention.

An explanation of the surprising effect achievable according to the invention may be based on the fact that the irregularity and unevenness of the working members imparts a certain turbulent motion to the material between the two discs, and the material may be moved also from any point of the disc towards its centre. For that reason the grinding cycle is irregular and the actual grinding operation is interrupted by longer or shorter intervals. Moreover, a large number of grooves and depressions extending substantially transversely to the discharge direction of the material will produce a multiplied cutting action on the material, which moves continuously along the cutting edges thus formed to render the grinding disc eminently suitable particularly for longfibrous material. Hay, maize, with cobs and leaves,

States Patent clover, green food, straw and green leaves, whether wet or dry, can be ground to controllable particle sizes in a single pass through the mill owing tothe repeated passage over the uneven cutting edges so that they can be fully digested and utilized by the digestive system of animals.

An illustrative embodiment of a grinding disc according to the invention is shown in the accompanying drawmgs.

Figs. 1 and 2 are top plan views of the stationary and rotary grinding discs, respectively.

Figs. 3a and 3b, respectively, are sectional views, taken on lines Illailla and IIIb-Illb of Figs. 1 and 2,

Fig. 4 is an enlarged top plan view of the surface of a disc, and

Figs. 5 and 6 respectively are sectional views taken on lines VV and VIVI of Fig. 4.

Another referred embodiment of the invention is shown in Figs. 7-9, in which Fig. 7 is a partly sectional elevation of the grinding discs,

Fig. 8 a top plan view of the central portion of the rotary disc and Fig. 9 a sectional view taken along line IX-IX of Fig. 8, showing a detail.

Fig. 10 is a top plan view showing a detail of Fig. l.

The inner working zone of the grinding discs, which are arranged in most cases vertically in a mill, comprises so-called chopping teeth distributed over the inner periphery of the disc. The stationary disc 1, which is disposed adjacent to the feed pipe and has a central inlet opening for the material to be ground, may have three such chopping teeth 2, each of which has a bead 3 protruding over the plane of symmetry of the two discs. The associated rotary disc 4, driven in a manner known, carries chopping teeth 5 of lower height, each of which has next to the inner periphery of the disc an extension 6 overlapping the bead 3 of the chopping teeth 2 of the stationary disc 1 (Figs. l-3a).

As is apparent from the drawings these chopping teeth of the two discs are not identical in form. In a manner known per se one chopping tooth of the stationaiy disc 1 is formed with a nose 7 extending into the disc cavity and below the extension 6 of the rotary disc whereas at least one of the chopping teeth of the rotary disc 4 has a crushing face 8, which is inclined towards the disc cavity and extends approximately parallel to the inner wall of the disc (shown in Fig. 3b).

Due to this shape of the chopping teeth, bulb material will drop farther down if the chopping tooth having the crushing face 8 is at the bottom, whereas the chopping tooth of the stationary disc formed with the nose 7 will prevent the material from rotating with the rotary disc; thus an effective action of the chopping teeth on the material is ensured.

The intermediate working zone of the grinding discs is formed by tearing teeth 9, which are inclined relative to the periphery of the disc and are arranged to cooperate like shears during the operation of the mill. The inner parts 10 of the tearing teeth lie in the plane of symmetry of the discs and extend approximately from the middle of the working face of the disc in the form of cutting edges 11 towards the inner periphery of the disc. Before reaching that inner periphery they merge at 12 into the inner wall of the disc (Figs. 4-6).

The tearing teeth 9 have groovelike recesses 13 formed in their surface by casting or grinding. Like the rib teeth these depressions are also of irregular arrangement, different width and depth and irregularly spaced. The teeth control the feed of the material to the grinding faces at the outer portion of the disc. During the passage through that zone the material is further torn and comminuted. It is suitable to form also the working faces of the chopping teeth 2 with such groovelike recesses 13 (Figs. 3a and 3b).

The outermost zone of the grinding discs comprises irregularly disposed discharge grooves 14, which extend substantially in the direction of the tearing teeth and differ in depth, width and inclination. The lands of the annular grinding zone which lie between these grooves 14 in the plane of symmetry are again interrupted by transverse grooves 15, which are also irregularly arranged, e.g. extend outwardly as at 16 or inwardly as at 17 or parallel to the rim of the disc as at 18 (Fig. 4). Thus the material is moved from one groove to another in a repeatedly changing course and in being thus moved is crushed and ground.

The material can be ground to a higher degree of fine ness if the annular grinding zone is provided with an arrangement of transverse grooves 19 (Fig. 1) which extend in spiral form over at least part of the grinding discs and whose walls are preferably recessed in the form of half a screw thread. This is shown more clearly in Fig. 10.

In another embodiment of the subject of the invention at least one row of substantially radially spaced catching teeth is provided in the central portion of the rotary disc inside the chopping teeth. These catching teeth cooperate with the nose of the chopping tooth of the stationary disc and consist suitably of boltlike projections which are arranged in the central portion of the rotary disc and terminate in an inclined end face.

This feature provides a further improvement of the method of operation and an increase in the capacity of such mills because the catching teeth arranged in the space cavity between the two grinding discs hook into greater chunks of the material to be ground, carry them along and force them during the further rotation of the grinding disc against the nose of the stationary chopping tooth. Thus the fruit is held fast, clamped and is milled off by the catching teeth during the continued operation of the mill. The chunk is still held to that nose of the chopping tooth until it has been divided then it is fed to the chopping teeth for the further grinding operation.

As is apparent from Figs. 7-9, the stationary disc 1 which is adjacent to the feed pipe 20 with its inlet opening 20' for the material to be ground has the same working formations as have been described in detail hereinbefore. The tearing teeth and discharged grooves are not shown in detail in the drawing. Fig. 7 shows one of the chopping teeth 2 with the bead 3'; this is the chopping tooth also formed with the nose 7 extending inwardly into the disc cavity.

Driven by a shaft 21 the rotary disc 4 is also of the type described hereinbefore. Fig. 7 shows one of its chopping teeth having an extension 6 extending below the head 3 of the chopping teeth. In this embodiment the central portion 22 of the rotary disc 4 is additionally provided with a number of substantially radially spaced catching teeth 23, as is apparent from Fig 8.

These catching teeth 23 consist of boltlike projections located in the central portion of the disc and terminating in end faces 24, which are inclined relative to the tooth axis (Fig. 9). Bores 25 provided in the central portion 22 serve for connecting the rotary disc 4 by means of fixing bolts 26.

The mill according to the invention is equally suitable for groats, fruit, green food, hay, cereal, bulb, sugar, crumb, coal etc. The material to be ground may be dry or moist. Thus the mill is suitable for operations for which beating mills were previously required.

What I claim is:

1. A grinding mill comprising a stationary grinding disc and a rotary grinding disc for cooperating with said stationary disc, each of said discs having a hollow conical working face facing the working face of the other disc, said working face of each disc having working formations arranged in a plurality of substantially annular zones, substantially all of the working formations of each zone differing in depth, width, configuration and distance from adjacent working formations of the same zone, the innermost of said zones of the rotary disc comprising at least one row of substantially radially spaced catching teeth, the next outer zone of the rotary disc comprising a plurality of chopping teeth, the innermost zone of the stationary disc comprising a plurality of chopping teeth adapted to cooperate with the chopping teeth of the rotary disc, one of said chopping teeth of the stationary disc having a nose which extends into the cavity defined between said working faces, said catching teeth being arranged to cooperate with said nose.

2. A grinding mill comprising a stationary grinding disc and a rotary grinding disc for cooperating with said stationary disc, each of said discs having a hollow conical working face facing the working face of the other disc, said working face of each disc having working forma tions arranged in a plurality of substantially annular zones, substantially all of the working formations of each zone differing in depth, width, configuration and distance from adjacent working formations of the same Zone, the innermost of said zones of the rotary disc comprising at least one row of substantially radially spaced catching teeth having boltlike extensions terminating in an inclined end face, the next outer zone of the rotary disc comprising a plurality of chopping teeth, the innermost zone of the stationary disc comprising a plurality of chopping teeth adapted to cooperate with the chopping teeth of the rotary disc, one of said chopping teeth of the stationary disc having a nose which extends into the cavity defined between said working faces, said catching teeth being arranged to cooperate with said nose.

3. A grinding disc for grinding mills, having a hollow conical working face formed with working formations arranged in a plurality of substantially concentric annular zones, substantially all of the working formations of each zone differing from each other and from the working formations of the other zones in depth, width, configuration, and distance from adjacent working formations of the same zone, the innermost one of said zones comprising at least one row of substantially radially spaced catching teeth having boltlike extensions terminating in an inclined end face.

References Cited in the file of this patent UNIT ED STATES PATENTS 382,747 Ames May 15, 1888 393,534 Brown Nov. 27, 1888 757,097 Deards et al. Apr. 12, 1904 782,293 Warner Feb. 14, 1905 1,091,654 Hamachek Mar. 31, 1914 1,183,350 Dellinger May 16, 1916 1,185,901 Hance June 6, 1916 1,556,323 Garza Oct. 6, 1925 1,556,870 Nelson Oct. 13, 1925 1,582,819 Holland-Letz Apr. 27, 1926 1,612,437 Holland-Letz Dec. 28, 1926 2,184,903 Baehr Dec. 26, 1939 FOREIGN PATENTS 451,390 Germany Oct. 26, 1927 

